The need for vertical adjustment of a work surface for a work desk such as a drafting table, operating table, work bench, or support for a computer terminal has long been recognized. Both the productivity and the comfort level of the individuals using the work desk are increased if the height of the work or support surface can be adjusted to fit the needs of a particular individual. Elaborate arrangements for such height adjustments have long been prevalent in such diverse areas as operating tables and drafting tables. In most cases, however, the adjustment has either been for a relatively small vertical travel or for adjustment to one of two distinct vertical positions, or has been elaborate and costly. The adjustments normally provided are frequently considered inadequate by users. For example, according to a recent report in Business Week (Nov. 5, 1984, p. 66), 70% of personal computer users surveyed complained about the lack of flexibility of their computer terminal desks.
It has been found that for some kinds of jobs the ability to switch between the standing and sitting position acts to relieve fatigue and therefore to improve productivity. If a work desk is to be used in either the standing or the sitting position, it is necessary to make a substantial vertical adjustment of the height of the work surface and desirable to have a nearly continuous vertical adjustment to provide the optimum surface height for short and tall operators. To meet this need, a work desk capable of continuous adjustment of the height of the work surface of about 15 inches with minimum adjustment effort and cost is needed. Gas spring actuated arrangements have been described for raising and lowering the height of the work surface of an operating table, but the height adjustment is limited to about eight inches, the travel of the movable part of a gas spring.
A further problem encountered in work desks with vertically adjustable work surfaces is that of achieving vertical motion without encountering a tendency to jam, while at the same time providing minimum play side support for the work surface. If the side supports are too tight, there will be a tendency for the work surface to jam when adjusted. If the side supports are not tight enough, there will be excessive play in the position of the work surface when it has been adjusted to the desired height.